HP 64783A, User Manual

Page: 692 / 816

When a software breakpoint instruction is executed, the processor initiates a
breakpoint-acknowledge cycle. This cycle signals the start of an entry into the
monitor. From this point on, stacking and the vector fetch proceed the same as for
a break entry. Unlike the interrupt-acknowledge cycle, the
breakpoint-acknowledge cycle is shown to the target system.
tck -u
tsto any
tg stat=11xxxxxxxx1x000xy
t
r 8
Line addr,H 68040 Mnemonic
----- -------- ------------------------------------------
-4 00000008 $484F0000 log sprog long read <- bkpt fetch
-3 0000000c $00000000 log sprog long read
-2 00000010 $01000000 log sprog long read
-1 00000014 $00000000 log sprog long read
0 00000000 $41------ bkpt ack (buserror) <- acknowledge
1 00000200 $0000040B mmu twalk data long read <- twalk stack
2 00000400 $0000060B mmu twalk data long read
3 0000063c $0000F01B mmu twalk data long read
4 0000f0ee $----0010 phy sdata word write <- stack format
5 0000f0ea $----0000 phy sdata word write <- stack PC high
6 0000f0ec $0008---- phy sdata word write <- stack PC low
7 00000200 $0000040B mmu twalk data long read <- twalk vector
8 00000400 $0000060B mmu twalk data long read
9 00000600 $0000009F mmu twalk data long read
10 00000010 $000016A2 phy sdata long read <- vector fetch
11 0000f0e8 $2700---- phy sdata word write <- stack SR
12 00000200 $0000040B twalk prog long read <- twalk monitor
13 00000400 $0000060B twalk prog long read
14 00000600 $0000101b twalk prog long read
15 000016a0 $007E2F0D phy sprog long read <- monitor
16 000016a4 $4BFAFA73 phy sprog long read
The only unique part of a breakpoint entry is the breakpoint-acknowledge cycle so
any problems will probably be related to this cycle. Because the emulator
internally responds to this cycle, it is not necessary for the target system to respond
to it. If the target system responds to this cycle with any wait states, the emulator
may become out of sync with the target system because the emulator terminates this
cycle immediately. If this causes a problem, it will show up on the cycle
immediately following the breakpoint-acknowledge cycle.
Chapter 18: Connecting the Emulator to a Target System
Installing Emulator Features
662